Our primary goal is to design topical peptide microbicides that will prevent sexually transmitted diseases (STDs) and remedial bacterial vaginosis (BV). A central element of this program involves designing Lactobacillus- sparing protegrin peptides that can inactivate C. trachomatis, kill C. albicans, and eliminate organisms associated with BV (e.g., Gardnerella, Mobiluncus, Prevotella). These peptides will also be tested against HIV-1, herpes simplex virus and Hemophilus ducreyii and Neisseria gonorrhoeae to identify those with broad-spectrum activity. The third project will analyze microbial mechanisms, especially efflux pumps, that allow gonococci to resist endogenous antimicrobial peptides such as LL-37. We will use this knowledge to identify and select protegrin variants that are poor substrates for such pumps. In the fourth project, we will delineate the endogenous antimicrobial polypeptides in vaginal secretions of normal women and subjects with BV. Characterizing the polypeptide effectors of innate resistance in normal vaginal secretions may illuminate the pathogenesis of various bacterial vaginitis/vaginosis syndromes. Protegrins remain the primary focus of this aspect of research. These small beta-sheet peptides were originally isolated from porcine leukocytes their unusually broad antimicrobial spectrum includes the major STD pathogens. During the past four years, we synthesized over 160 protegrin variants and used them to define the structural elements required for activity against bacteria, C. albicans and HIV-1. Although PG-1,our lead molecule, is very active vaginal lactobacilli, we have constructed Lactobacillus-sparing protegrin variants that retain excellent activity against STD agents and BV-associated organisms. Further "fine-tuning" of these protegrin variants will allow us to identify peptides for future in vivo testing in appropriate models. Overall, these studies will facilitate the development of novel, peptide- containing topical microbicides specifically designed for vaginal use. Given the high prevalence of STDs and their serious personal and economic consequences, such topical microbicides are urgently needed.